In a molding process, air is accumulated within the mold so as to mix with the material within the mold. As a result, the product produced from the mold will accumulate with air so as to affect the quality of the product. Thus, generally, the mold is formed with a plurality of air holes for releasing air within the mold. However, the air holes will cause the material within the mold to accumulate in the air holes so that the outer surface of the product produced from the mold is formed with protrusions which are formed of the material accumulated in the holes.
Thus, there is a demand for a novel design which can improve the above mentioned prior art defects.